Arc-lamp.



w. A. DARRAH.

ARC LAMP.

APPLICATION FILED on. s. 1913.

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WILLIAM A. DABRAH, 0F WILKINSBURG, HOUSE ELECTRIC AND MANUFACTURI SYLVANIA.

PENNSYLVANIA, ASSIGNOR TO WESTING- NG COMPANY, A CORPORATION OF PENN- ARC-LAMP.

Specification of Letters Patent.

Patented Oct. 15, 1918.

Application filed October 8, 1913. Serial N 0. 793,094.

To all whom it may conoerm Be it known that I, WILLIAM A. DARRAH, a citizen of the United States, and a resident of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Arc-Lamps, of which the following is a specification.

My invention relates to electric arc lamps, and it has special reference to those commonly known as flaming and luminous arc lamps.

More particularly, my invention relates to electric arc lamps which are of the nonfocusing type and of the character indicated above.

The tendency of present are lamp development indicates that simplification of regulating and feeding mechanisms is essential in order to decrease manufacturing cost, the cost of attendance and maintenance, and the charge against depreciation. In pursuance of this policy, non-focusing arc lamps have been proposed.

To obtain the maximum illuminating efficiency of an arc lamp, it is necessary to preclude the accumulation of light-absorbing deposits upon the surfaces of the arc-inclosing globe. Inasmuch as electrodes adapted for use in flaming and luminous arc lamps yield fumes and vapors, when consumed at the arc, provision must be made either for withdrawing the fumes and vapors from the arc chamber by. an adeguatecirculatin sys tem communicating w1th the outer air, or for causing them to.condense and deposit upon portions of the lamp structure other than the surface of the arc-inclosing globe.

Extensive experiments have demonstrated that, in order to maintain theentire inner surface of the arc-inclosing globe of a nonfocusing flaming or luminous arc lamp in the most effective operating condition, it is important to embody in the arc lamp structure, a'means for creating a defined circulating system for the gases evolved from the are that shall be entirely internal.

1 One object of my invention isto provide, in an arc lamp, more particularly oneof the non-focusing type, a means for developing a defined internal circulating system, therebyprecluding the accumulation of deposits upon the inner surface of the arc-inclosing globe. However, it willbe understood that my invention may be applied to are lamps other than the type herein disclosed, the function and operation of my invention being applicable to the various forms and types of arc lamps.

For a better understanding of the nature and scope of my invention, reference may be had to the following description and the accompanying drawing, the single figure of which is a View, partially in elevation and partially in section, of an arc lamp that em bodies a form of my invention.

The lampof the present invention is provided with a main globe 1 of frusto-conical shape, having double walls 2 and 3 and inclosing a substantially air tight chamber 4 known as an arc chamber. By means of an annular passage way 5, the arc chamber 4 may communicate with a condensing or cooling chamber 6 which is closed against the circulation of atmospheric air. Walls 7 of the condensing chamber are made of heatradiating material with an exposed surface of large area relative to the cubical contents of the chamber, which insures that the said walls shall be maintained cool during the operation of the lamp. An outer globe 8 of any preferred form substantially incloses the main globe 1, a chamber 9 within the outer globe being cut off from communication with the cooling chamber 6 by an an nular member 10 and being closed throughout to exclude atmospheric air.

At the beginning of a trim, an upper electrodell engages a stationary holder 12, and a cooperating lower electrode 13 engages the arc regulating mechanism (not shown) of the lamp, said regulating mechanism being of any suitable well known type and being contained in a chamber located in the upper portion of a pedestal 14. As the electrode 11 is consumed, the flame or are between the opposing ends of the electrodes travels upwardly while the lower electrode 13 is fed into the are by the regulating mechanism of the lamp. Because of the length of travel of the arc during the consumption of the electrodes, the vertical dimensions of the arc-inclosing globe l are large, ascompared with the corresponding dimensions of globes of the usual types of construction. If the globe 1 were of the usual type, its inner walls would not be uniformly heated by the arc, and, consequently, a clean inner surface could not bemaintained.

In my lamp, the arc-inclosing globe 1 comprises walls 2 and 3 which are spaced apart a short distance to inclose a dead air space 15 It is essential that the air space 15 -be closed from the circulation therethrough of atmospheric air, and that the walls 2 and 3 be of similar contour, thus utilizing to a maximum degree the heat insulating, qualities which are provided by the dead air space 15. Moreover, the walls 2 and 3 are closer to the arc at the beginning of the trim, because of the frusto-conical shape of the globe 1, than they are after the upper electrode has been burned for a time. As a result, the lower portions of the wall 2 are maintained very hot, thereby compensating in some degree for the long circulating path that the evolved gases must traverse before being admitted into the condensing chamber 6. lnasmuch as the lower portion of the globe 1 is kept hot by reason of the proximity of the walls to the arc, deposits which may afiect the light-transmitting qualities of the globe, are substantially precluded from forming thereupon.

The distance between the adjacent walls 2 and 3 of the globe 1 should be short in order to insure a substantially uniform value for the heat gradient between the arcinclosing chamber a and the chamber 9. It is also essential that .the air contained within the chamber 15 be of small volume so as not to absorb a large quantity of heat generated by the arc at the beginning of the operation of the lamp. This conserves a large amount of heat for absorption by the wall 2 which incloses the arc chamber 4. The dead air space 9 prevents a rapid conduction of heat in the outer wall 3 of the globe 1 and thereby maintains the wall 2 at a substantially high and uniform temperature.

The upper electrode 11 is provided with an axially and longitudinally extending opening 16 which communicates with the condensing chamber 6 substanially as shown in the drawing. A division device 17, positioned within the condensing chamber 6, engages the electrode holder 12, thus providing two compartments within the condensing chamber, namely, a central and outer compartment intercommunicating at the upper portion of the chamber. I prefer that the division device 17 have the form of an inverted and conically shapedshell which, in combination with the opening 16 of theupper electrode, forms a flue for the arc gases, as will hereinafter be explained. A deflector 18, disposed within the annular assage way 5 is secured to the electrode ho der 12 in any desired manner.

During the operation of the lamp, the gases and fumes evolved from the arc, by reason of the consumption of the electrodes, will be drawn by an up-draft through the central openin 16 of the upper electrode 11. The division device 17 directs the flow of the said gases against the upper walls of the condensing chamber 6 which are main-' tained cool at all times because of their large heat-radiating capacity. When the gases are sufiiciently cooled, they condense and deposit their suspended material upon the inner surfaces of the walls 7, thus precluding" the accumulation of gaseous deposits upon the inner walls 2 of the inclosing globe 1. The gases which have been cleansed of their suspended particles are returned into the arc-inclosing chamber 4 throu h the pas sage way 5-by a down-draft. he deflector 18, having substantially the form shown in the drawing, directs the downward flow of the cleansed ases longitudinally and adjacent to the inner surface of the arc globe wall 2, thereby, permitting the clean. gases to wash, as it were, the inner surface of the globe 1.

It will be ap rent that, when the arc is positioned at t 'e lower portionof the arc chamber 4 at the beginning of the trim, the cleansed gases will wash substantially theentire inner surface of the wall 2. As the arc ascends. duringthe consumption of the electrodes, the lower portion of the walls will be kept free from deposit by reason of the heat insulating. jackets formed by the dead air spaces 15 and 9. Again, the soot and heavier combustion particles will be caught in the comparatively strong up draft through the opening 16 in the upper electrode 11, thus preventing the accumulation of such matter upon the arcing end of the lower electrode 1 Inasmuch as I have provided a defined circulating system which does not involve communication with either the outer air or the dead air space 9, and which deposits the particles of combustion and condensation in a condensing chamber, I have embodied within my lamp allthe advantages accruing 11p to the usual type of a focusing arc lamp which is provided with an air-tight con densing chamber, an inner globe closed at its bottom and communicating therewith, and an outer globe by means of which a. dead air space isprovlded around the inner globe.

While I have herein described a specific embodiment of my invention, it is not-intended that the invention shall be limited to this particular embodiment. It will be apparent to anyone skilled in the art that changes maybe made in the structure with-. out departing from the spirit of my invention. p j

I claim, as my invention: 7

1. In an electric arc lamp, the combinetion with a closed globe providing an airtight arc chamber, a condensing chamber, and means defining a substantially annular passageway between the said globe and the said condensing chamber, of an electrode secured to the said means and provided with a longitudinally extending opening which, in combination with said annular passageway, provides a path for creating an upward and direct flow of gases evolved from the arc into the condensing chamber and a downward flow of gases through the said annular passalgeway into the arc chamber.

2. 11 an electric arc lamp, the combination with an arc-inclosing globe, a condensing chamber, means definin an annular passageway between the said g obe and the said condensing chamber, and comprising a division device dividing the said condensing chamber into an inner and aninter-communicating outer compartment, the latter only communicating freely with the arcdnclosing globe through said annular passageway, of an electrode suspended from the said division device and provided with a longitudinally extending opening affording communication between the arc chamber and the said inner compartment only of the condensing chamber, said electrode opening providing means for an updraft therethrough for the arc gases evolved in the arc.

3. In an electric arc lam the combination with an arc-inclosing lbbe, a condensmg chamber, and means de nin an annular passageway between the said g obe and the said condensing chamber, and a division device dividing the condensing chamber into inner and outer compartments, said compartments communicating at the upper portion only of the condensing chamber, of an electrode suspended from the said division device and provided with a longitudinally extending opening affording communication between the arc chamber and the said inner compartment, communication between the outer compartment of the condensing chamber and the arc inclosing globe being provided by said annular passageway.

In testimony whereof, I have hereunto subscribed my name this 26th day of Sept.

WILLIAM A. DARRAH- Witnesses: I

B. B. Hmns, M. C. METZ.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patentl, Washington, D. G. 

